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Dong YN, Mercado-Ayón E, Coulman J, Flatley L, Ngaba LV, Adeshina MW, Lynch DR. The Regulation of the Disease-Causing Gene FXN. Cells 2024; 13:1040. [PMID: 38920668 PMCID: PMC11202134 DOI: 10.3390/cells13121040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 06/10/2024] [Accepted: 06/13/2024] [Indexed: 06/27/2024] Open
Abstract
Friedreich's ataxia (FRDA) is a progressive neurodegenerative disease caused in almost all patients by expanded guanine-adenine-adenine (GAA) trinucleotide repeats within intron 1 of the FXN gene. This results in a relative deficiency of frataxin, a small nucleus-encoded mitochondrial protein crucial for iron-sulfur cluster biogenesis. Currently, there is only one medication, omaveloxolone, available for FRDA patients, and it is limited to patients 16 years of age and older. This necessitates the development of new medications. Frataxin restoration is one of the main strategies in potential treatment options as it addresses the root cause of the disease. Comprehending the control of frataxin at the transcriptional, post-transcriptional, and post-translational stages could offer potential therapeutic approaches for addressing the illness. This review aims to provide a general overview of the regulation of frataxin and its implications for a possible therapeutic treatment of FRDA.
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Affiliation(s)
- Yi Na Dong
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Jennifer Coulman
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Liam Flatley
- The Wharton School, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Lucie Vanessa Ngaba
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Miniat W. Adeshina
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - David R. Lynch
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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2
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Belbellaa B, Reutenauer L, Messaddeq N, Monassier L, Puccio H. High Levels of Frataxin Overexpression Lead to Mitochondrial and Cardiac Toxicity in Mouse Models. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 19:120-138. [PMID: 33209958 PMCID: PMC7648087 DOI: 10.1016/j.omtm.2020.08.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 08/27/2020] [Indexed: 12/18/2022]
Abstract
Friedreich ataxia (FA) is currently an incurable inherited mitochondrial disease caused by reduced levels of frataxin (FXN). Cardiac dysfunction is the main cause of premature death in FA. Adeno-associated virus (AAV)-mediated gene therapy constitutes a promising approach for FA, as demonstrated in cardiac and neurological mouse models. While the minimal therapeutic level of FXN protein to be restored and biodistribution have recently been defined for the heart, it is unclear if FXN overexpression could be harmful. Indeed, depending on the vector delivery route and dose administered, the resulting FXN protein level could reach very high levels in the heart, cerebellum, or off-target organs such as the liver. The present study demonstrates safety of FXN cardiac overexpression up to 9-fold the normal endogenous level but significant toxicity to the mitochondria and heart above 20-fold. We show gradual severity with increasing FXN overexpression, ranging from subclinical cardiotoxicity to left ventricle dysfunction. This appears to be driven by impairment of the mitochondria respiratory chain and ultrastructure, which leads to cardiomyocyte subcellular disorganization, cell death, and fibrosis. Overall, this study underlines the need, during the development of gene therapy approaches, to consider appropriate vector expression level, long-term safety, and biomarkers to monitor such events.
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Affiliation(s)
- Brahim Belbellaa
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch 67404, France.,Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch 67404, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch 67404, France.,Université de Strasbourg, Illkirch 67404, France
| | - Laurence Reutenauer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch 67404, France.,Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch 67404, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch 67404, France.,Université de Strasbourg, Illkirch 67404, France
| | - Nadia Messaddeq
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch 67404, France.,Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch 67404, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch 67404, France.,Université de Strasbourg, Illkirch 67404, France
| | - Laurent Monassier
- Laboratoire de Pharmacologie et Toxicologie NeuroCardiovasculaire EA7296, Faculté de Médecine, Strasbourg 67085, France
| | - Hélène Puccio
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch 67404, France.,Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch 67404, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch 67404, France.,Université de Strasbourg, Illkirch 67404, France
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3
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Mazzara PG, Muggeo S, Luoni M, Massimino L, Zaghi M, Valverde PTT, Brusco S, Marzi MJ, Palma C, Colasante G, Iannielli A, Paulis M, Cordiglieri C, Giannelli SG, Podini P, Gellera C, Taroni F, Nicassio F, Rasponi M, Broccoli V. Frataxin gene editing rescues Friedreich's ataxia pathology in dorsal root ganglia organoid-derived sensory neurons. Nat Commun 2020; 11:4178. [PMID: 32826895 PMCID: PMC7442818 DOI: 10.1038/s41467-020-17954-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 07/28/2020] [Indexed: 12/31/2022] Open
Abstract
Friedreich's ataxia (FRDA) is an autosomal-recessive neurodegenerative and cardiac disorder which occurs when transcription of the FXN gene is silenced due to an excessive expansion of GAA repeats into its first intron. Herein, we generate dorsal root ganglia organoids (DRG organoids) by in vitro differentiation of human iPSCs. Bulk and single-cell RNA sequencing show that DRG organoids present a transcriptional signature similar to native DRGs and display the main peripheral sensory neuronal and glial cell subtypes. Furthermore, when co-cultured with human intrafusal muscle fibers, DRG organoid sensory neurons contact their peripheral targets and reconstitute the muscle spindle proprioceptive receptors. FRDA DRG organoids model some molecular and cellular deficits of the disease that are rescued when the entire FXN intron 1 is removed, and not with the excision of the expanded GAA tract. These results strongly suggest that removal of the repressed chromatin flanking the GAA tract might contribute to rescue FXN total expression and fully revert the pathological hallmarks of FRDA DRG neurons.
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Affiliation(s)
- Pietro Giuseppe Mazzara
- Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
- Department of Neuroscience, The Scripps Research Institute, 92037, La Jolla, CA, USA
| | - Sharon Muggeo
- Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Mirko Luoni
- Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Luca Massimino
- Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Mattia Zaghi
- Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | | | - Simone Brusco
- Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Matteo Jacopo Marzi
- Center for Genomic Science of IIT@SEMM, Istituto Italiano di Tecnologia (IIT), 20139, Milan, Italy
| | - Cecilia Palma
- Department of Electronics, Information & Bioengineering, Politecnico di Milano, 20133, Milan, Italy
| | - Gaia Colasante
- Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Angelo Iannielli
- Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
- National Research Council (CNR), Institute of Neuroscience, 20129, Milan, Italy
| | - Marianna Paulis
- Humanitas Clinical and Research Center, 20089, Rozzano, Milano, Italy
| | - Chiara Cordiglieri
- National Institute of Molecular Genetics "Romeo e Enrica Invernizzi" - INGM, 20122, Milan, Italy
| | - Serena Gea Giannelli
- Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Paola Podini
- Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Cinzia Gellera
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133, Milan, Italy
| | - Franco Taroni
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133, Milan, Italy
| | - Francesco Nicassio
- Center for Genomic Science of IIT@SEMM, Istituto Italiano di Tecnologia (IIT), 20139, Milan, Italy
| | - Marco Rasponi
- Department of Electronics, Information & Bioengineering, Politecnico di Milano, 20133, Milan, Italy
| | - Vania Broccoli
- Division of Neuroscience, San Raffaele Scientific Institute, 20132, Milan, Italy.
- National Research Council (CNR), Institute of Neuroscience, 20129, Milan, Italy.
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Li J, Li Y, Wang J, Gonzalez TJ, Asokan A, Napierala JS, Napierala M. Defining Transcription Regulatory Elements in the Human Frataxin Gene: Implications for Gene Therapy. Hum Gene Ther 2020; 31:839-851. [PMID: 32527155 PMCID: PMC7462031 DOI: 10.1089/hum.2020.053] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 05/26/2020] [Indexed: 12/20/2022] Open
Abstract
Friedreich's ataxia (FRDA) is the most common inherited form of ataxia in humans. It is caused by severe downregulation of frataxin (FXN) expression instigated by hyperexpansion of the GAA repeats located in intron 1 of the FXN gene. Despite numerous studies focused on identifying compounds capable of stimulating FXN expression, current knowledge regarding cis-regulatory elements involved in FXN gene expression is lacking. Using a combination of episomal and genome-integrated constructs, we defined a minimal endogenous promoter sequence required to efficiently drive FXN expression in human cells. We generated 19 constructs varying in length of the DNA sequences upstream and downstream of the ATG start codon. Using transient transfection, we evaluated the capability of these constructs to drive FXN expression. These analyses allowed us to identify a region of the gene indispensable for FXN expression. Subsequently, selected constructs containing the FXN expression control regions of varying lengths were site specifically integrated into the genome of HEK293T and human-induced pluripotent stem cells (iPSCs). FXN expression was detected in iPSCs and persisted after differentiation to neuronal and cardiac cells, indicating lineage independent function of defined regulatory DNA sequences. Finally, based on these results, we generated AAV encoding miniFXN genes and demonstrated in vivo FXN expression in mice. Results of these studies identified FXN sequences necessary to express FXN in human and mouse cells and provided rationale for potential use of endogenous FXN sequence in gene therapy strategies for FRDA.
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Affiliation(s)
- Jixue Li
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Yanjie Li
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jun Wang
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Trevor J. Gonzalez
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Aravind Asokan
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Surgery, Duke University School of Medicine, Durham, North Carolina, USA
| | - Jill S. Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Marek Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
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5
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Ventosa M, Wu Z, Lim F. Sustained FXN expression in dorsal root ganglia from a nonreplicative genomic HSV-1 vector. J Gene Med 2017; 19:376-386. [PMID: 29044877 DOI: 10.1002/jgm.2993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/06/2017] [Accepted: 10/07/2017] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Friedreich's ataxia (FA) is an autosomal recessive neurodegenerative disease caused by mutations in the frataxin gene (FXN), which lead to reduced levels of the essential mitochondrial protein frataxin. Currently, there is no effective cure. METHODS With the aim of developing a gene therapy for FA neuropathology, we describe the construction and preliminary characterization of a high-capacity nonreplicative genomic herpes simplex virus type 1 vector (H24B-FXNlac vector) carrying a reduced version of the human FXN genomic locus, comprising the 5-kb promoter and the FXN cDNA with the inclusion of intron 1. RESULTS We show that the transgene cassette contains the elements necessary to preserve physiological neuronal regulation of human FXN expression. Transduction of cultured fetal rat dorsal root ganglia neurons with the H24B-FXNlac vector results in sustained expression of human FXN transcripts and frataxin protein. Rat footpad inoculation with the H24B-FXNlac vector results in human FXN transgene delivery to the dorsal root ganglia, with expression persisting for at least 1 month. CONCLUSIONS The results of the present study support the feasibility of using this vector for sustained neuronal expression of human frataxin for FA gene therapy.
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Affiliation(s)
- Maria Ventosa
- Department of Neurosurgery, University of Michigan and VA Ann Arbor Healthcare System, Ann Arbor, MI, USA
| | - Zetang Wu
- Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System, Ann Arbor, MI, USA
| | - Filip Lim
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Madrid, Spain
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6
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Pérez-Luz S, Gimenez-Cassina A, Fernández-Frías I, Wade-Martins R, Díaz-Nido J. Delivery of the 135 kb human frataxin genomic DNA locus gives rise to different frataxin isoforms. Genomics 2015; 106:76-82. [PMID: 26027909 DOI: 10.1016/j.ygeno.2015.05.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/21/2015] [Accepted: 05/23/2015] [Indexed: 11/25/2022]
Abstract
Friedreich's ataxia (FRDA) is the most common form of hereditary ataxia caused by recessive mutations in the FXN gene. Recent results have indicated the presence of different frataxin isoforms due to alternative gene expression mechanisms. Our previous studies demonstrated the advantages of using high-capacity herpes simplex virus type 1 (HSV-1) amplicon vectors containing the entire FXN genomic locus (iBAC-FXN) as a gene-delivery vehicle capable of ensuring physiologically-regulated and long-term persistence. Here we describe how expression from the 135 kb human FXN genomic locus produces the three frataxin isoforms both in cultured neuronal cells and also in vivo. Moreover, we also observed the correct expression of these frataxin isoforms in patient-derived cells after delivery of the iBAC-FXN. These results lend further support to the potential use of HSV-1 vectors containing entire genomic loci whose expression is mediated by complex transcriptional and posttranscriptional mechanisms for gene therapy applications.
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Affiliation(s)
- S Pérez-Luz
- Departamento Biología Molecular and Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, 28049 Madrid, Spain; CIBER de Enfermedades Raras (CIBERER), Spain; Instituto de Investigación Sanitaria Puerta de Hierro-Majadahonda, Spain
| | | | - I Fernández-Frías
- Departamento Biología Molecular and Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, 28049 Madrid, Spain; CIBER de Enfermedades Raras (CIBERER), Spain; Instituto de Investigación Sanitaria Puerta de Hierro-Majadahonda, Spain
| | | | - J Díaz-Nido
- Departamento Biología Molecular and Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, 28049 Madrid, Spain; CIBER de Enfermedades Raras (CIBERER), Spain; Instituto de Investigación Sanitaria Puerta de Hierro-Majadahonda, Spain.
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7
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Li Y, Polak U, Bhalla AD, Rozwadowska N, Butler JS, Lynch DR, Dent SYR, Napierala M. Excision of Expanded GAA Repeats Alleviates the Molecular Phenotype of Friedreich's Ataxia. Mol Ther 2015; 23:1055-1065. [PMID: 25758173 DOI: 10.1038/mt.2015.41] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 03/03/2015] [Indexed: 12/21/2022] Open
Abstract
Friedreich's ataxia (FRDA) is an autosomal recessive neurological disease caused by expansions of guanine-adenine-adenine (GAA) repeats in intron 1 of the frataxin (FXN) gene. The expansion results in significantly decreased frataxin expression. We report that human FRDA cells can be corrected by zinc finger nuclease-mediated excision of the expanded GAA repeats. Editing of a single expanded GAA allele created heterozygous, FRDA carrier-like cells and significantly increased frataxin expression. This correction persisted during reprogramming of zinc finger nuclease-edited fibroblasts to induced pluripotent stem cells and subsequent differentiation into neurons. The expression of FRDA biomarkers was normalized in corrected patient cells and disease-associated phenotypes, such as decreases in aconitase activity and intracellular ATP levels, were reversed in zinc finger nuclease corrected neuronal cells. Genetically and phenotypically corrected patient cells represent not only a preferred disease-relevant model system to study pathogenic mechanisms, but also a critical step towards development of cell replacement therapy.
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Affiliation(s)
- Yanjie Li
- Department of Biochemistry and Molecular Genetics, UAB Stem Cell Institute, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Urszula Polak
- Department of Epigenetics and Molecular Carcinogenesis, Center for Cancer Epigenetics, University of Texas MD Anderson Cancer Center, Science Park, Smithville, Texas, USA; Department of Cell Biology, Poznan University of Medical Sciences, Poznan, Poland
| | - Angela D Bhalla
- Department of Biochemistry and Molecular Genetics, UAB Stem Cell Institute, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Natalia Rozwadowska
- Department of Biochemistry and Molecular Genetics, UAB Stem Cell Institute, University of Alabama at Birmingham, Birmingham, Alabama, USA; Institute of Human Genetics, Polish Academy of Science, Poznan, Poland
| | - Jill Sergesketter Butler
- Department of Biochemistry and Molecular Genetics, UAB Stem Cell Institute, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - David R Lynch
- Division of Neurology and Pediatrics, Children's Hospital of Philadelphia, Abramson Research Center, Philadelphia, Pennsylvania, USA
| | - Sharon Y R Dent
- Department of Epigenetics and Molecular Carcinogenesis, Center for Cancer Epigenetics, University of Texas MD Anderson Cancer Center, Science Park, Smithville, Texas, USA
| | - Marek Napierala
- Department of Biochemistry and Molecular Genetics, UAB Stem Cell Institute, University of Alabama at Birmingham, Birmingham, Alabama, USA; Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland.
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8
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Sarsero JP, Holloway TP, Li L, Finkelstein DI, Ioannou PA. Rescue of the Friedreich ataxia knockout mutation in transgenic mice containing an FXN-EGFP genomic reporter. PLoS One 2014; 9:e93307. [PMID: 24667739 PMCID: PMC3965543 DOI: 10.1371/journal.pone.0093307] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 03/03/2014] [Indexed: 11/18/2022] Open
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive disorder characterized by neurodegeneration and cardiomyopathy. The presence of a GAA trinucleotide repeat expansion in the first intron of the FXN gene results in the inhibition of gene expression and an insufficiency of the mitochondrial protein frataxin. We previously generated BAC-based transgenic mice containing an FXN-EGFP genomic reporter construct in which the EGFP gene is fused in-frame immediately following the final codon of exon 5a of the human FXN gene. These transgenic mice were mated with mice heterozygous for a knockout mutation of the murine Fxn gene, to generate mice homozygous for the Fxn knockout mutation and hemizygous or homozygous for the human transgene. Rescue of the embryonic lethality that is associated with homozygosity for the Fxn knockout mutation was observed. Rescue mice displayed normal behavioral and histological parameters with normal viability, fertility and life span and without any signs of aberrant phenotype. Immunoblotting demonstrated the production of full-length frataxin-EGFP fusion protein that appears to act as a bifunctional hybrid protein. This study shows frataxin replacement may be a viable therapeutic option. Further, these mice should provide a useful resource for the study of human FXN gene expression, frataxin function, the evaluation of pharmacologic inducers of FXN expression in a whole-animal model and provide a useful source of cells for stem cell transplantation studies.
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Affiliation(s)
- Joseph P. Sarsero
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Royal Children’s Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children’s Hospital, Parkville, Victoria, Australia
| | - Timothy P. Holloway
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Royal Children’s Hospital, Parkville, Victoria, Australia
| | - Lingli Li
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Royal Children’s Hospital, Parkville, Victoria, Australia
| | - David I. Finkelstein
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia
| | - Panos A. Ioannou
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Royal Children’s Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children’s Hospital, Parkville, Victoria, Australia
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9
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Li L, Voullaire L, Sandi C, Pook MA, Ioannou PA, Delatycki MB, Sarsero JP. Pharmacological screening using an FXN-EGFP cellular genomic reporter assay for the therapy of Friedreich ataxia. PLoS One 2013; 8:e55940. [PMID: 23418481 PMCID: PMC3572186 DOI: 10.1371/journal.pone.0055940] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 01/03/2013] [Indexed: 11/18/2022] Open
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive disorder characterized by neurodegeneration and cardiomyopathy. The presence of a GAA trinucleotide repeat expansion in the first intron of the FXN gene results in the inhibition of gene expression and an insufficiency of the mitochondrial protein frataxin. There is a correlation between expansion length, the amount of residual frataxin and the severity of disease. As the coding sequence is unaltered, pharmacological up-regulation of FXN expression may restore frataxin to therapeutic levels. To facilitate screening of compounds that modulate FXN expression in a physiologically relevant manner, we established a cellular genomic reporter assay consisting of a stable human cell line containing an FXN-EGFP fusion construct, in which the EGFP gene is fused in-frame with the entire normal human FXN gene present on a BAC clone. The cell line was used to establish a fluorometric cellular assay for use in high throughput screening (HTS) procedures. A small chemical library containing FDA-approved compounds and natural extracts was screened and analyzed. Compound hits identified by HTS were further evaluated by flow cytometry in the cellular genomic reporter assay. The effects on FXN mRNA and frataxin protein levels were measured in lymphoblast and fibroblast cell lines derived from individuals with FRDA and in a humanized GAA repeat expansion mouse model of FRDA. Compounds that were established to increase FXN gene expression and frataxin levels included several anti-cancer agents, the iron-chelator deferiprone and the phytoalexin resveratrol.
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Affiliation(s)
- Lingli Li
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Lucille Voullaire
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Chiranjeevi Sandi
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Mark A. Pook
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Panos A. Ioannou
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children’s Hospital, Parkville, Victoria, Australia
| | - Martin B. Delatycki
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children’s Hospital, Parkville, Victoria, Australia
- Department of Clinical Genetics, Austin Health, Heidelberg, Victoria, Australia
| | - Joseph P. Sarsero
- Cell and Gene Therapy, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children’s Hospital, Parkville, Victoria, Australia
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